Electronic control system for echo-ranging apparatus



ISAAC P RODMAN l P RODMAN 2,540,035

ELECTRONIC CONTROL SYSTEM FOR ECHO-HANGING APPARATUS ONE Filed Sept. 23, 1944 muhtimvamh Jan. 30, 1951 Patented Jan. 30, 1951 ELECTRONIC CONTROL SYSTEM FOR ECHO-RANGING APPARATUS Isaac P. Rodman, Cambridge, Mass., assignor to .the" United States of America as represented by the Secretary of the Navy Application September 23, 1944, Serial No. 555,539

12 Claims. 1

The present invention relates in general to wave-energy ranging and direction indication systems and more particularly to an electronic training and keying control system of special utility in an underwater sound echo ranging and direction indicating system.

The main object of the invention is the provision of an automatic search control system capable of controlling the keying and training of the directional transducer of an underwater sound echo ranging and direction indicating system in proper sequence to carry out a predetermined methodical search for underwater objects and through simple electronic means.

Another object is the provision of a system of the above type having adjustability of the keying interval or periodicity; adjustability of the unit of intermittent angular training movement of the directional transducer, and adjustability of the length or duration of signal impulse or ping.

Another object is to provide a circuit arrangement whereby a single discharge tube of the thyratron type will-afford adequate control of an alternating current motor for training the sound projector or electrosonic transducer.

Another object is the provision of electronic means for assuring operation of the keying.

' invention will become apparent upon a perusal of the following description and the accompanying drawing which is a diagrammatic representation of a preferred form of the invention.

Referring to the drawing in detail, a power transformer I -I furnishes voltages of positive and negative sign relative to a common ground or intermediate potential, from the lower half 01' its center-tapped high voltage secondary Hi. This is accomplished by connecting the ccnter tap i-l to a common ground or return connection G and the lower terminal I2 in branch connection through a pair of opposed rectifiers V-IA and V-IB with associated filter circuits R-l, R-2, C-i, and R--|6, R-l'i, (1-9, and voltage regulators tubes V--2 and V-3, respectively, to the common ground or return connection G. A switch 8-2 is inserted in the branch connection from the transformer to the first rectifier-filter circuit. Thus a constant voltage, positive relative to ground, may be maintained at the terminal I3 while a constant voltage, negative relative to ground, is maintained at the terminal 14. The rectifier-s V-IA and V-IB here used are formed each from one half of a twin triode each grid being connected directly to its associated plate element to form the anode of a diode rectifier. In the present embodiment the power transformer T-l receives an alternating current of 115 volts in its primary winding, developing 290 volts across the two secondary sections each side of the tapii. to ground, while the voltage regulator tubes 2 microfarad condenser -5 through a discharge tube V4, preferably a thyratron, and a suitable choke coil L-l the lower side of the condenser C5 being connected to ground as is the lower or negative side of condenser C6. The thyratron V4 has its shield grid connected to the cathode and is controlled by connection of its control grid through a 1 megohm resistor R8 to the center point of a potentiometer R-S. The latter is connected at its upper terminal through a 2 megohm resistor R-4 to the junction of the timing condenser C6 with the choke coil L-i, and at its lower terminal through a 150,000 ohm resistor R6 and an additional 2 megohm resistor R'! to the negative power supply point M of 150 volts negative with respect to the intermediate or ground potential. Thus the tube V-4 acts as a pulsing tube whose pulsing interval is determined by the setting of the potentiometer R-5. To prevent a negative charge from collecting on the upper side of the condenser C-5, the condenser is bridged by a rectifier V-5A of which latter the cathode is connected to the upperside of the condenser. In the present embodiment the rectifier V5A is comprised of a triode used as a diode rectifier by connection of its anode and grid, and constituting one half of a twin triode of which the other half is the rectifier V-5B used in another portion of the system to be later described. Condenser 0-5 is connected for control of a relay tube V-B, preferably a thyratron, through a resistors Rl8 and R-l 9 connected to the negative power supply terminal 14 and ground. respectively. The adjustable center tap from the potentiometer RIl connects through a 2 megohm rcsistor R-IZ to the control grid of the thyratron V-B. The plate of the thyratron is connected through the primary winding of a preferably one-to-one transformer T-2 to the 290 volt source of alternating current provided by the second or-upper half of the power trans- 55 former secondary winding, the cathode of the 69 when the plate is positive, the grid is connected to the ungrounded terminal of the 6.3 volt heater winding l6 of the power transformer which latter is so phased as to be degrees out of phase with the plate voltage. A reversing switch 8-! provides reversible connection .of a one microfarad condenser 6-2 and one winding W-l of the training motor M in multiple across the terminals of the primary winding of transformer T--2. The other winding of the training motor is connected through a one microfarad condenser 6-3 to the 115 'volt alternating current source indicated-on the diagram by the legend "115 v. A. C. The motor M may be the training motor of any echo range and direction indicating system such as indicated by the trainable directional electrosonic-transducer I'I, indicator l8, transmitter l9 and keying-relay contact 20.

' To insure operation of the keying relay 2| only during non-operation of the training motor and substantially immediately after cessation of an operation of the motor, the secondary winding of the transformer T--2 by induction, takes alternating electrical energy from the motor energizing-circuit which is rectified and filtered through rectifier V-IA and a filter circuit comprised of condenser C1 and resistors R-ll and R/l 5, to apply a substantially continuous charging potential to a one microfarad condenser C8 through a rectifier V-IB arranged to conduct in the direction of the charging current. Thus so long as the motor is running the condenser O8 is kept under a substantially continuous charging potential. Upon cessation of energization of the transformer, the condenser C-8 may discharge through resistors R-24 and R-i3 producing a difiference in potential across the terminals of resistor R-M acting through resistors R-22 and R23 to render less negative the normally blocking negative potential on the grid of akeyingcontrol triode V-SB which controls the keying relay 2|. One terminal of the relay connects through the triode V5B to the common ground while the other terminal connects with one of the ungrounded terminals of the divided secondary of the power transformer at a potential of 290 volts relative to ground. A condenser CI0 smooths the self-rectified plate current of the triode V-5B.

Normally-blocking negative potential is applied to the grid of triode V5B from the source of negative potential at M through resistors R-2l and R-23. The rate of discharge of condenser C8 through R24 and R-ll and consequently the duration of resultant reduction in negative bias on the control grid sufficient to maintain the triode conducting, is determined by adjustment of the variable resistor 3-43. A normally open contact on the keying relay 2| operates to connect the transmitter [8 with the directional transducer while another normally open contact 22 on the same relay operates to close a discharge or scavenging circuit for the condenser C5 through a low-value spark-suppressing resistor R-ill. y

In the specific embodiment of the invention here described for the" sake of disclosure, the several pairs of triodes, or triodes connected as diodes for use as rectifiers, specifically the pairs of triodes VIA and V--IB, V5A and V-SB, and V'|A and V-lB, are each the two halves of a single-envelope twin triode. However it will be understood that single trlodes or other equivalents of these components may be substituted therefor without change in function or departure from the inventive concept. a

Operati0n.With the switches S-l and S-2 closed, the storage condenser C-6 is continuously charged through 100,000 ohm resistor R! 4 until the negative bias on the control grid of the thyratron tube V-l is reduced to a value permitting the tube to fire, the charging time-interval being determined by adjustment of the voltage divider R-i. Firing oi the tube V-! charges condenser (2-5 from condenser 0-4, the electrical inertia of the choke coil L-I ins'uring the quenching of the tube. At this instant the positive voltage applied to the voltage divider R5 is reduced permitting the negative grid bias to become more negative thereby pre-. venting the tube V-4 from refiring. The positive charge on condenser C5 now acting through .voltage divider R-ll opposes the negative bias on the control grid of the second thyratron V-8 to an extent to permit this tube to become conductive and complete a circuit for pulsating current from the upper 290-volt ungrounded terminal oi the power transformer through the primary of transformer T-2 or motor winding and tube V6 to ground. This causes the training motor M to operate in the direction determined by the reversing switch S3 which operation continues until the charge on condenser (2-5 reduces to a point permitting the bias on tube V-S to become sumciently negative to block the tube. This time interval and consequently the degree of angular movement of the transducer I1 is determined by the adjustment of the potentiometer R-i l.

During this operation of the motor M, the

energizatlon of the transformer T-2 by the pulsating current through its primary winding causes an alternating electrical potential to be generated at the terminals of the secondary winding by induction. This energy is rectified and filtered by the rectifier V'|A and filter network C-I, Ri4 and R,-l5, to maintain a substantially continuous charging potential on condenser C-8 through rectifier V-IB the latter being arranged to provide a relatively high conductive path of current flow from ground to the positive side of condenser 0-8 for rapid charging of the condenser at the polarity indicated. Immediately that the motor energizing circuit through transformer T--2 is opened at the thyratron V6 the storage condenser 0-8 starts to discharge through resistors R-M and Rl3, the voltage drop across Rr-Z opposing the negative bias on the control grid of the triode V-BB to make the bias less negative and permit the triode to close the energizing circuit of the keying-relay 2|. This closes the keying contact 20 to operatively connect the transmitter iii to the transducer H to cause the latter to project a signal pulse or ping of a length or duration determined by the adjustment of the variable resistor R- -I3 in the discharge circuit of condenser C'8. Substantially simultaneously with the closure of' keying-relay contact 20, the contact 22 on the same relay closes to effect a relatively rapid scavenging discharge of the condenser 0-5, again opening upon de-energization of the relay and readying the condenser 0-5 for another measured charge.

After a predetermined interval of time the cycle of operations above narrated is repeated. This interval or periodicity of the cycle is determined by the adjustment of potentiometer R-i, the time-constant of the condenser 0-6 and resistor R3 for the voltage used, and the nor mal bias on the tube V-l, and is preferably considerably greater than the round-trip time 01 the signal between the transducer and the reflecting object plustht training interval plus 5 the duration of the signal pulse so that the reflection or echo of the signal pulse may be received at the indicator through the transducer without interference from a succeeding or outgoing pulse. a

Manual control of slewing the transducer in either direction is accomplished by closure of the slewing push-button switch which grounds the grid side of the biasing potentiometer R. 01

the motor control tube V--6, the direction of ro-.- tation being determined by the position of the reversing switch S-3.

From the foregoing description it will he seen that it is possible to make adjustments in any one or more of the values of keying rate, degrees of training per cycle and length of pins, without affecting any of the others. It will also be noted that even where manual control of slewing is resorted to, pinging is automatically. withheld, by action of the secondary winding of transformer T-2, during operation of the motor.

In one practical embodiment of the invention certain of the components indicated in the drawing are of the values and qualities noted below.

Condensers C--i 4 microfarads -2, 1 microfarad 0-3, 1 microfarad C4, 4 microfarads 0-5, 5 microfarads 0-6, 1 microfarad 0-1, 0.5 microfarad 400 volts 0-8, 1 microfarad 0-9, 4 microfarads C-i 0, 2 microfarads Resistanoes T-2, "Ferranti H Keying relay :1 is a 6500 61m 2-contact relay type AQC3C.

While but one specific embodiment of the in vention is herein shown and described for the sake of disclosure, it is to be understood that the invention is not limited to such specific embodiment but contemplates all such modifications and variants thereof as tall fairly within the scope oi the appended claims.

1. In an underwater sound echo ranging apparatus having a directional transducer and a. transmitter adapted to actuate the transducer to emit a pulse of sound wave energy. means to train the transducer step-by-step in a given direction of rotation periodically through successive predetermined arcs, means to vary the predetermined arc movement of said transducer training means, means to vary the periodicity of the op' eration of said transducer training means, keying means to energize the transducer from th transmitter to emit a pulse of sound wave energy substantially immediately following each training movement, said means being variable to control the duration of an emitted sound pulse.

2. In an underwater sound echo ranging apparatus having a directional transducer and a transmitter adapted to actuate the transducer to emit a pulse of sound wave energy, means to train the transducer step-by-step in a given direction of rotation periodically through successive predetermined arcs, means to vary the predetermined arc movement of said transducer training means, means to vary the periodicity of the operation of said transducer training means, means operable at the cessation of each training movement to energize the transducer from the transmitter, and means to vary the duration of an emitted sound pulse.

3. Apparatus in accordance with claim 1, in which said periodicity varying means includes a normally non-conducting thermionic tube and a control therefor which allows said tube to conduct at intervals by alterin the grid potential of said tube, charge storing means filled upon firing of said tube, a second normally non-conducting tube having a control electrode connected to said charge storing means, whereby said second tube conducts'whenever the potential of said charge storing means exceeds a predetermined value, and a training motor operated by power transmitted through said second tube when conducting.

4. In an underwater sound echo ranging ap paratus having a directional transducer and a transmitter adapted to actuate the transducer to emit a pulse of sound wave. energy, means to train the transducer step-by-step in a given direction of rotation periodically through successive predetermined arcs, said means including a normally non-conducting tube which is made conducting during the training period, and a training motor to which current is supplied by said tube when conducting, means to vary the periodicity of the operation of said training means, keying means to energize the transducer from the transmitter to emit pulses of sound wave energy following each training movement. said last means being variable to' control the duration of an emitted pulse.

5. Apparatus in accordance with claim 1 in which said keying means includes a normally non-conducting thermionic tube having a con trol electrode, charge storing means connected to said electrode, means to charge said last means during each training movement, whereby, upon cessation of each said training movement, the charge storing means raises the potential of said 'controlelectrode and causes said tube to conduct, and a connection in the anode circuit of hence the period of operation, being dependent on the potential and the time constant of the voltage divider and capacitor.

' 7. In an underwater echo ranging and direction indicating system, a tralnable electrosonic transducer, means for automatically training the transducer step-by-step in a given direction of rotation through predetermined successive arcs of movement and energizing the transducer for a predetermined interval of time at the end of each training movement, means for varying the period of the cycle, means for varying the interval of time of energization of the transducer, and means'ior varying the extent of said successive training movement.

8. In anunderwater ranging and direction indicating system a tralnable electrosonic transducer, a transmitter adapted to actuate the transducer to emit pulses of sound wave energy, a keying relay to effect actuation of the transducer from the transmitter, a training motor for the transducer, an energizing circuit for the training motor energized intermittently to train the transducer step-by-step in a given direction,

said storage means and differential conducting means offering a low impedance to chargingcurrent to said storage means and a relatively high impedance to discharge-current from said storage means, whereby said relay is actuated to key the transmitter after each step of movement of the transducer.

9. In an underwater echo ranging and direction indicating system, a tralnable electrosonic transducer, a transmitter to actuate the transducer to emit pulses of wave energy, a keying relay to eifect actuation of the transducer from the transmitter, a training motor for the transducer, an energizing circuit for the training motor energized intermittently to train the transducer step-by-step in a given direction, elecwhereby energization of the relay is prohibited during energization of the motor. I

10. In an underwater echo ranging and direction indicating system, a tralnable electrosonic transducer, a transmitter for actuating the transducer to emit signal pulses, a keying relay controlling operative connection of the transmitter with the transducer, 9. training motor for the transducer, an energizing circuit for the motor, electrical storage means, a normally non-conducting tube operable when conducting to maintain energization of the motor and having a control electrode connected to said storage meanswhereby the tube conducts whenever the potential of said storage means exceeds a predetermined value, a second electrical storage means operable during discharge to maintain energization of the keying relay, means taking energy irom the training motor circuit only during energization of the training motor to apply a charging potential to said second storage means, and

means operable during energization of the key.-

ing relay to maintain said first storage means in discharged condition, and means for intermittently charging said first storage means whereby the transducer is trained step-by-step in a given direction and the transmitteris keyed only .at the end of each training step.

11. In an underwater ranging and direction indicating system, a tralnable electrosonic trans! ducer, a normally non-conducting tube and a.

ing motor for the transducer operated by power.

transmitted through said second tube when conducting, and a, current rectifier device connected across the terminals of said storage means to prevent reversal of polarity of the storage means, whereby the'training motor is operated to train the transducer step-by-step at predetermined intervals.

12. In an underwater ranging and direction inv dicating system, a tralnable electrosonic transducer, a transmitter adapted to actuate thetransducer to emit pulses of wave energy. .8

transformer having primary and secondary windings, an electronic control tube of the thyratron type connected in series with the primary winding and a source of alternating current-to complete the series circuit when the tube is conduct ing, an alternating-current training motor for the transducer connected across the terminalsof the primary winding, a condenser connected in multiple with the primary winding and the motor, a keying-control circuit controlling operative connection oi the transmitter with the transducer, charge storing means for energizing said control circuit when discharging, and means deriving electrical energy from said secondary winding to charge said storing means and prevent discharge during energization of the transformer, whereby the transmitter is connected with the transducer only during discharge of the storage means after a training movement has stopne ISAA) P. RODMAN.

REFERENCES CITED I The following references are of record in the file of this patent:

UNITED, STATES PATENTS Number Name Date 2,083,344 Newhouse et al June 8, 1937 2,225,046 Hunter Dec. 1'7, 1940 2,231,929 Lyman Feb. 18, 1941 4 FOREIGN PATENTS Number Country Date 546,202 Great Britain July 2, 1943 

